Alkylammonium thiocyanate

Table 3.5-1 lists the E values for the alkylammonium thiocyanates and nitrates and the substituted imidazolium salts. It can be seen that the values are dominated by the nature of the cation. Eor instance, values for monoalkylammonium nitrates and thiocyanates are ca. 0.95-1.01, whereas the two tetraalkylammonium salts have values of ca. 0.42-0.46. The substituted imidazolium salts lie between these two extremes, with those with a proton at the 2-position of the ring having higher values than those with this position methylated. This is entirely consistent with the expected hydrogen bond donor properties of these cations. 

Certain nitriles add amines to form N-substituted amidines. This reaction has been modified and extended through the use of ammonia and alkyl- or aryl-ammonium salts of sulfonic acids. Many amidines have been prepared in yields ranging from 13% to 86%. Some amidines are obtained in better yields by heating a cyanide with ammonium thiocyanate or an alkylammonium thiocyanate."... 

PILs containing alkylammonium cations have been investigated for their potential use in chromatography, such as eAN, ° ethylammonium acetate (EAA), ° pro-pylammonium nitrate (PAN), ° tributylammonium nitrate (TB AN), ° alkylammonium formates, and various alkylammonium thiocyanates. The early use of PILs in chromatography was primarily to characterize the solvent properties of the PILs, which was described in a comprehensive review by Poole in 2004. The solvent properties of PILs that make them potentially useful in chromatography are that they are polar, are cheap, are easy to make, can be miscible with water, can be air/moisture stable, and have high selectivity toward solutes that are polar and/or hydrogen donors or acceptors. 

Coddens ME, Furton KG, Poole CF (1886) Synthesis and gas chromatographic stationary phase properties of alkylammonium thiocyanates. J Chromatogr 356 59-77... 

So far, it was found that these two cryptands are able to dissolve a variety of primary alkylammonium tetraphenylborates in methylene chloride which confirmed that the inclusion complexes are formed instantly . Furthermore, cryptands 10 and 11 dissolve potassium thiocyanate", hence, cascade binding may also be envisaged. These preliminary results encouraged more systematic complexation studies which are still in progress. 

The nature of the anion also affects the surface activity of the water-soluble cationic surfactants. The surface activity of tetra-butylammonium salts at the water-air and water-hexane interfaces reduces in the order iodiode > bromide > chloride [77,78]. Boguslavsky et al. reported that the adsorption equihbrium constant and the adsorption at the water-octane interface are higher for tetra-alkylammonium bromides as compared to chlorides [76,79]. The influence of the counterions on the adsorption of alkylpyridinium salts at the water-air interface was studied. It was estab-hshed that the salts lowered the surface tension in the sequence perchlorate > thiocyanate > iodide > bromide > chloride [80-83]. The anion influence on the work of adsorption was found to increase with the growth of the concentration of the surface-active salt [83]. 

Alkylthiocyanates have been prepared in higji yield by reaction of alkali metal thiocyanates with various primary and secondary alkyl halides under phase transfer conditions. Quaternary alkylammonium salts [12—14], crown ethers [15], cryptates [16], and tertiary amines [14] have all proved effective phase transfer catalysts for this reaction (Eq. 13.7 and Table 13.4). The mechanism of the thiocyanate displacement is probably similar to that of the cyanide displacement reaction (see Sect. 7.2). 

The chiral macrocyclic polyether (U)-d-(521) and its (5)-D-diastereoisomer have been derived from D-mannitol and (R)- or (S )-binaphthol, respectively. Significant changes were observed in the n.m.r. spectra of (/ )-d-(521) and its diastereoisomer in the presence of primary alkylammonium salts [e.g. (+)-(2 )-, (-)-(5 )- and ( )-(i 5 )-a-phenylethylammonium hexafluorophos-phate], indicating that both diastereoisomers act as hosts to suitable guest molecules. The chiral hosts dd-(523) and dd-(524) have been obtained from l,2 5,6-di-0-isopropylidene-D-mannitol by the routes outlined in Scheme 100. The temperature dependence of the H n.m.r. spectrum of the 1 1 complex of dd-(524) and benzylammonium thiocyanate in [ Ha]dichloromethane was interpreted... 

About the earliest study of molten organic salts was the measurement of surface tensions by Walden of a number of alkylammonium nitrates, thiocyanates, and halides. Most recently the chlorides have been studied by Kisza and Hawranek. The surface tensions of these salts are similar to those for organic liquids and they range from 20 to 50 dyn/cm. These... 

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